2.8 Understanding radiationApril 11, 2023

Key terms

• Nucleus: the inner part of the atom where protons and neutrons are found

• Radiation: energy spreading out, as carried by electromagnetic radiation or a particle

• Ionising radiation: radiation that can remove electrons from atoms, causing the atom to become positively charges

• Non-ionising radiation: radiation that does not remove electrons from atoms (e.g. microwaves or infra-red)

http://upload.wikimedia.org/wikipedia/commons/d/d7/Alphadecay.jpg

Alpha (α) radiation

• Alpha radiation consists of α particles• These are He nuclei, each having two

protons and two neutrons and a charge of +2

• When α particles hit other particles they knock electrons off them, this leaves the particles with a positive charge

• The particles have been ionised• α particles are highly ionising

Penetration

• Alpha particles are large compared with beta and gamma so are much less penetrating

• Only a few cm of air or a sheet of paper will stop them, they cannot get through out skin!

Beta (β) radiation

• Beta radiation consists of fast-moving electrons that have been given off by unstable nuclei

• If they collide with an atom that can also knock off electrons and ionise the atom

• They are small so are only moderately ionising

Penetration

• They are much smaller than alpha so much more penetrative

• They can travel through a few mm of Aluminium before being absorbed

• They are moderately penetrating so will go through your skin and are a danger to living organisms

Gamma (γ) radiation

• Gamma radiation is a type of electromagnetic radiation, it has a very short wavelength and is emitted from unstable nuclei

• EM radiation has no charge so cannot readily ionise but due to its large energy can weakly ionise

• Because it is weak it can travel through aluminium and several cm of lead

• It will easily pass through the human body• It can also create Hulks

Using alpha

• Alpha radiation is used in smoke detectors. A weak source ionised the air and causes a small current to flow. If smoke gets into the detector the current is affected and the alarm goes off

Using beta

• Beta radiation is used to monitor the thickness of paper during production. A GM tube is used to monitor how much radiation gets through which changes the pressure on the rollers

Using gamma

• Gamm radiation is used to kill bacteria in food for long term storage. It is also used in the treatment of cancer

Questions

• Describe two properties each of alpha, beta and gamma radiation and an application of each

• Describe the applications and dangers of radiation